Final answer:
The components needed for the adaptation phase of the CRISPR-Cas system are Cas1 and Cas2, as they are responsible for integrating foreign DNA into the host genome for future defense.
Step-by-step explanation:
The adaptation phase of the CRISPR-Cas system, which is part of the prokaryotic adaptive immune system, involves the integration of foreign DNA segments into the CRISPR loci of the host genome. This phase requires two specific proteins: Cas1 and Cas2. After a virus infects a prokaryotic cell, Cas1 and Cas2 excise a piece of the viral DNA and insert it into the CRISPR array as a new spacer. This integration step is crucial because it provides the cell and its progeny the ability to 'remember' the virus for future defense.
Since both Cas1 and Cas2 are involved in this process, the correct answer to which components are needed for the adaptation phase of the CRISPR-Cas system is D. Cas1 and Cas2.